句型转换
____ She often does her homework at night. (变为否定句)
She                              her homework at night.
____ We are cleaning our classroom now. (对划线部分提问)
                  you          now?
____ He likes pandas because they are very cute. (对划线部分提问)
                he        pandas?
____ I think he is in the classroom.（改为否定句）
I        think he        in the classroom.
____ Mr Black is a doctor.（对划线部分提问）
                Mr Black         ?

已知：如图，B、E分别是AC、DF上一点，∠1=∠2，∠C=∠D．求证：∠A=∠F．

  17－9=（  ）

物体做匀加速直线运动，其加速度的大小为5 m/s²，那么，在任意1秒内（   ）